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The mean score in a certain test is 80. If the test scores

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by M7MBA » Sun Nov 24, 2019 1:07 pm
The mean score in a certain test is 80. If the test scores have a normal distribution and the standard distribution is 7, what percent of examinees score between 66 and 94?

A) 50%
B) 68%
C) 82%
D) 96%
E) 98%

[spoiler]OA=D[/spoiler]

Source: Princeton Review
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by Brent@GMATPrepNow » Mon Nov 25, 2019 6:47 am
M7MBA wrote:The mean score in a certain test is 80. If the test scores have a normal distribution and the standard distribution is 7, what percent of examinees score between 66 and 94?

A) 50%
B) 68%
C) 82%
D) 96%
E) 98%

[spoiler]OA=D[/spoiler]

Source: Princeton Review
This type of question would never appear on the GMAT.
The GMAT does not test one's knowledge of the normal distribution.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by Scott@TargetTestPrep » Fri Dec 13, 2019 1:07 pm
M7MBA wrote:The mean score in a certain test is 80. If the test scores have a normal distribution and the standard distribution is 7, what percent of examinees score between 66 and 94?

A) 50%
B) 68%
C) 82%
D) 96%
E) 98%

[spoiler]OA=D[/spoiler]

Source: Princeton Review
Since (66 - 80)/7 = -2 and (94 - 80)/7 = 2, we see that the scores from 66 to 94, inclusive, are within 2 standard deviations of the mean. Therefore, by the 68-95-99.7 rule, approximately 95% of the examinees' scores are between 66 and 94, inclusive.

Answer: D

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